OAHelper Topics
Practice coding questions by topic.
Build depth in the topics that appear repeatedly across real online assessments: arrays, graphs, dynamic programming, strings, trees, SQL, heaps, and more.
Array
3154 real OA questions
Math
1683 real OA questions
Greedy
1481 real OA questions
String
1419 real OA questions
Simulation
1355 real OA questions
Sorting
1320 real OA questions
Aptitude
1118 real OA questions
Hash Table
1098 real OA questions
Dynamic Programming
1034 real OA questions
Counting
691 real OA questions
Prefix Sum
662 real OA questions
Binary Search
550 real OA questions
Logical Reasoning
503 real OA questions
Two Pointers
483 real OA questions
Depth-First Search
476 real OA questions
Matrix
418 real OA questions
Graph
414 real OA questions
Tree
411 real OA questions
Bit Manipulation
388 real OA questions
Breadth-First Search
385 real OA questions
Graph Theory
372 real OA questions
SQL
332 real OA questions
Number Theory
322 real OA questions
Verbal Ability
311 real OA questions
Heap (Priority Queue)
295 real OA questions
Sliding Window
293 real OA questions
Quantitative Aptitude
289 real OA questions
Enumeration
280 real OA questions
Combinatorics
276 real OA questions
Data Interpretation
212 real OA questions
Data Structures
209 real OA questions
Stack
199 real OA questions
Database
198 real OA questions
Design
198 real OA questions
aptitude
191 real OA questions
Shortest Path
189 real OA questions
Arithmetic
175 real OA questions
Machine Learning
175 real OA questions
Percentages
166 real OA questions
Python
155 real OA questions
logical-reasoning
144 real OA questions
Recursion
135 real OA questions
Union Find
127 real OA questions
Probability
125 real OA questions
Queue
119 real OA questions
Binary Tree
115 real OA questions
Operating Systems
109 real OA questions
Geometry
108 real OA questions
array
106 real OA questions
Java
99 real OA questions
Linked List
96 real OA questions
Backtracking
94 real OA questions
greedy
92 real OA questions
Aggregation
91 real OA questions
math
90 real OA questions
Binary Indexed Tree
89 real OA questions
Monotonic Stack
88 real OA questions
Mechanical Engineering
87 real OA questions
C
85 real OA questions
Reading Comprehension
84 real OA questions
Segment Tree
84 real OA questions
String Matching
82 real OA questions
quantitative-aptitude
82 real OA questions
Algorithms
81 real OA questions
C++
80 real OA questions
dynamic-programming
78 real OA questions
Statistics
77 real OA questions
Union-Find
75 real OA questions
Numerical Ability
74 real OA questions
Computer Networks
73 real OA questions
simulation
72 real OA questions
Memoization
71 real OA questions
Topological Sort
67 real OA questions
string
67 real OA questions
DBMS
66 real OA questions
OOP
66 real OA questions
Ordered Set
66 real OA questions
Ratio and Proportion
65 real OA questions
Averages
64 real OA questions
Bitmask
63 real OA questions
Computer Architecture
63 real OA questions
counting
63 real OA questions
Grammar
62 real OA questions
Output Prediction
62 real OA questions
sorting
60 real OA questions
Pointers
58 real OA questions
Puzzles
57 real OA questions
verbal-ability
57 real OA questions
C Programming
54 real OA questions
Linux
53 real OA questions
Join
52 real OA questions
Group By
51 real OA questions
combinatorics
50 real OA questions
critical-reasoning
49 real OA questions
data-interpretation
49 real OA questions
Algebra
48 real OA questions
Arrays
48 real OA questions
Deep Learning
48 real OA questions
Divide and Conquer
48 real OA questions
Fundamentals
48 real OA questions
Profit and Loss
48 real OA questions
Seating Arrangement
48 real OA questions
machine-learning
48 real OA questions
percentages
48 real OA questions
Critical Reasoning
47 real OA questions
Number Series
47 real OA questions
Time and Work
47 real OA questions
Trie
45 real OA questions
hash-table
45 real OA questions
Minimum Spanning Tree
43 real OA questions
Networking
43 real OA questions
English
42 real OA questions
Time Complexity
42 real OA questions
Vocabulary
42 real OA questions
Generative AI
41 real OA questions
Monotonic Queue
41 real OA questions
Data Sufficiency
40 real OA questions
Direction Sense
38 real OA questions
Sweep Line
38 real OA questions
Brainteaser
36 real OA questions